Overview
ISO/TS 23165:2006 - "Geometrical product specifications (GPS) - Guidelines for the evaluation of coordinate measuring machine (CMM) test uncertainty" provides guidance for evaluating the test uncertainty when performing the ISO 10360-2 acceptance and reverification tests. It explains how to quantify the uncertainty required by ISO 14253-1 decision rules so testers can make rational conformance/non‑conformance decisions at a specified confidence level.
Key topics and technical requirements
- Scope and purpose: Guidance for applying the ISO 10360-2 test by evaluating the test uncertainty associated solely with the testing equipment and its use (the tester’s responsibility).
- Definitions: Clear definitions of test uncertainty, tester, tester counterpart, and coefficient of thermal expansion (CTE) for the material standard of size.
- Uncertainty models:
- Probing error (P): the standard uncertainty u(P) is evaluated from the material standard’s documented form error and its uncertainty (see the standard’s equation and Annex A for the full model).
- Error of indication (E) for size measurements: u(E) is expressed as the root-sum-square of principal contributors - calibration uncertainty of the material standard, uncertainty due to the material’s CTE, temperature measurement, misalignment, and fixturing.
- Expanded uncertainty: U(P) = k · u(P) and U(E) = k · u(E) with coverage factor k = 2 (typical).
- Tester responsibility: Only those uncertainty components under the tester’s control are included. Instrumental errors of the CMM (which form part of P or E) are not included as contributors to test uncertainty.
- Annexes: Annex A (background and error models), Annex B (alternative material standards), Annex C (numerical examples of uncertainty budgets), Annex D (relation to the GPS matrix).
Practical applications
- Performing acceptance and reverification tests on CMMs to support procurement decisions, installation qualification, or periodic verification.
- Preparing uncertainty budgets for test reports required by ISO 14253-1 decision rules.
- Supporting quality assurance in metrology labs and manufacturing when proving conformance or non‑conformance of measuring equipment.
- Informing contracts between suppliers, purchasers and third‑party testers about how test uncertainty is to be assessed and reported.
Who should use this standard
- Metrology and calibration laboratories
- CMM manufacturers and suppliers
- Quality managers and engineers responsible for measurement systems
- Inspection and verification personnel performing ISO 10360‑2 tests
Related standards
Keywords: ISO/TS 23165:2006, CMM test uncertainty, Geometrical product specifications, GPS, ISO 10360-2, ISO 14253-1, probing error P, error of indication E, measurement uncertainty.
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